But as the full results rolled in, the representative from Harlem's lead shrank, to 802 votes, prompting a manual count of every remaining absentee and affidavit ballot. On Thursday, New York Board of Elections officials began painstakingly tallying roughly 2,000 paper ballots to determine if Rangel will, in fact, be headed back to Congress next year.

As of Thursday evening, seven of the disputed assembly districts' ballots had been counted and Rangel's lead had grown to 945 votes, or about 2.4 percent of the 40,000 ballots cast, according to the Board of Elections.

It's highly unlikely the remaining ballots will strip Rangel of his ever-growing lead, but as long as the count drags on, his victory can't be certified. (Rangel was once head of the powerful House Ways and Means Committe, but stepped down from that post after facing multiple ethics violations, for which he was censured in December 2010, just a month after easily winning reelection.)

Espaillat, Rangel's opponent, has called for a full recount and even a possible re-do election, but Rangel's margin of victory would have to shrink to one half of one percent to trigger a recount. A re-do election would require court intervention, which Espaillat filed for on Tuesday.

Espaillat's charges allege voter suppression and claim that many of the ballots that were deemed invalid are from Latino voters who supported him. As a Dominican-American, he was counting on support from the Hispanic community to oust long-time incumbent Rangel.

New York Judge John Carter ruled Thursday morning that after the hand count is complete, the Board of Elections could not certify a winner without the court's approval, leaving the door ever-so-slightly open that the court could mandate a recount or re-do election.

After all of the absentee and affidavit ballots are counted, election officials will re-examine the ballots that were originally discarded. Both Espaillat and Rangel can challenge each of the ballots that the election's board deems invalid, sparking court proceedings that could further delay a final election result.

Espaillat spokesman Ibrahim Khan said it was "hard to say" whether Espaillat will be able to overturn Rangel's preliminary win.

"We want to make sure that this is a process where we count every single vote," Khan told ABC News.

In a fundraising email to supporters on Monday, Rangel sounded confident that his win would stand.

"To my surprise, my opponent's campaign pounced on me on Friday, saying that I had somehow stolen their votes! I'm completely baffled by the situation and the way my opponent has been reacting," Rangel wrote in the email.

"I don't know what will transpire in the coming days, but one thing is clear: I need your help to prepare myself for another battle--whether it's a legal battle with the Board of Elections or with my opponent."